Psilopsida

plural noun

Psi·​lop·​si·​da

sīˈläpsədə

: a subdivision of Tracheophyta comprising vascular plants with no roots, leaves only partially differentiated or lacking, no leaf traces, a usually protostelic vascular cylinder, and the sporangia merely terminal enlargements of the stem compare lycopsida , pteropsida , sphenopsida

Word History

Etymology

New Latin, from psil- + -opsida (as in lycopsida)

Love words?

You must — there are over 200,000 words in our free online dictionary, but you are looking for one that’s only in the Merriam-Webster Unabridged Dictionary.

Start your free trial today and get unlimited access to America's largest dictionary, with:

• More than 250,000 words that aren't in our free dictionary
• Expanded definitions, etymologies, and usage notes
• Advanced search features
• Ad free!